STIMULATION OF THE ANTIOXIDANT SYSTEM THROUGH SELENIUM IN SACCHAROMYCES CEREVISIAE

Selenium (Se) has important functions in humans and animals, such as improving the immune system. It is also a component of many enzymatic proteins, including glutathione peroxidase (GPx), which fights free radicals. Because of this, it is a micronutrient used to enrich yeasts, but it can be toxic at higher concentrations, making it impossible to use the microorganism. In order to develop viable yeasts with a high content of antioxidant enzymes for the subsequent production of food supplements, the aim of this study was to determine the effect of selenium on the accumulation of antioxidant enzymes in Saccharomyces cerevisiae thermosacc yeast cells. The parameters to be analyzed were cell viability and the enzymatic activity of GPx and glutathione reductase (GR). The cells were grown in corn hydrolysate medium containing the following concentrations of sodium selenite: 0 mg L-1 (T1); 200 mg L-1 (T2) and 400 mg L-1 (T3). The treatments were carried out in quintuplicates with 150g L-1 of sugar, for 10 hours at a temperature of 30˚C ± 2˚C in a shaker, with controlled agitation (130 rpm). The enzymes were quantified using MERCK® tests and read on a spectrophotometer. As a result, the highest enzymatic activity of GPx and GR was obtained in the T3 treatment of 4,18±0,2 and 3,48±0,15 µmol/mg of protein, respectively. Regarding cell viability, the best treatment was T1, without the addition of sodium selenite, with 93% viability, while treatments T2 and T3 obtained 90,34±0,21 and 87.87±0,33% cell viability respectively, (p<0,05). Although sodium selenite was a limiting factor in cell viability, mainly due to the osmotic stress it causes, T3 reached the end of cultivation with high viability. It can be concluded that the treatment with the highest enzymatic activity was T3, despite having the lowest viability of 87.87%.